release: Add /boot/loader.conf to some cloudware

These were forgotten during the METALOGization process earlier.

Approved by: re (cperciva)
Reviewed by: markj
MFC after: immediately (for 15.0-RC2)
Differential Revision: https://reviews.freebsd.org/D53795

(cherry picked from commit 86c63597f2dc7f89268d13a00c0dc7a74cca51d0)
(cherry picked from commit 0e737642f27546ea34229447b2bc056a1fa58799)